1. Field of the Invention
The present invention relates to a blade brake for use in a walk-behind lawn mower, and more particularly for use in a self-propelled, walk-behind lawn mower. More specifically, this invention is directed to a blade brake assembly for use in a lawn mower having a lawn mower deck, including a mower blade, a power deck including a pair of drive wheels, and a motor, wherein the lawn mower deck is pivotable with respect to the power deck for changing the cutting height.
2. Description of the Related Art
Although the present invention has utility in walk-behind snow blowers, power sweepers or the like, the most common utilization of the invention is anticipated for lawn mowing equipment of the commercial type and particularly to large capacity, walk-behind, self-propelled mowers of the commercial type. Consequently, except where otherwise expressly stated, the description herein is directed to walk-behind lawn mowing equipment and in particular to commercial type lawn mowers.
Commercial type self-propelled, walk-behind lawn mowers commonly have a power deck containing two drive wheels and handle bars supporting operating handles for various control functions, including gear selection, power take-off engagement/disengagement, speed controls for each wheel, etc. The mower deck is supported by a structure having caster wheels and extending forward from the power deck.
In such mowers, a blade brake function, specified by ANSI requirements is often accomplished by attaching a band brake on a spindle of one of the mower blades. When the band brake is activated, the mower blade stops. If there are multiple mower blades, usually tied together with a belt, if one blade stops, then the remaining blades will also stop because the first blade has stopped. Such band brake may be activated when the power take-off unit is disengaged (or turned off). Usually the power take-off unit is disengaged by operating a lever. Often, such a lever will move an idler pulley operating on a belt transferring power between the motor and the mower deck, into a position where there is no longer tension on the belt, and thus no longer drive to the mower deck. When the power take-off lever causes such disengagement, an actuator operatively connected to the power take-off disengagement lever will then operate the band brake. Since the actuator is mounted on the power deck, which is stationary, and the band brake is mounted on the mower deck, which pivots, a problem arises with the band brake when raising or lowering the mower deck to different cutting height settings, when the actuator is connected directly to the band brake.
For example, if a mower deck is pivoted at a forward portion thereof, for movement up and down to change the cutting height, the actuator for actuating the band brake must somehow adjust for the movement of a mower deck in changing the cutting height.
Accordingly, there is difficulty in properly adjusting such a blade brake to accommodate maximum and minimum cutting height without requiring an accompanying adjustment of the blade brake. For example, if the blade brake is properly set for a high mower deck position, the brake may not disengage when the mower deck is pivoted to the low position. On the other hand, if it is set and adjusted for the low mower deck position, the brake may not engage when the mower deck is pivoted to a high position. Because the mower deck pivots while the engine and power deck remain stationary, in the high mower deck position the blade brake may actually be closer to the idler pulley, which is the point of actuation for the brake linkage. At the same time, the deck drive pulley may be closer to the engine pulley which makes the idler pulley rotate more. Thus, when the actuation of the blade brake occurs directly from the actuator for the idler pulley, the differences in height and distance to the blade brake will cause the problem described above.